Now to mass carbon monoxide poisingen at a restaurant on new York's Long Island. One person killed. Dozens getting sick. The restaurant wasn't required to have a carbon monoxide date detect detector. Reporter: Overnight, officials confirming what caused a deadly leak at a New York restaurant Saturday reaching. Defective heating E quumt in the building. Specifically a flue pipe on one of the water heaters failed. Reporter: A woman passed out at an upscale restaurant. When first responders arrived, they started feeling sick, too. Evacuated that restaurant and others. They were trying to get everybody out as fast as they could. Reporter: 27 employees and first responders were hospitalized. A restaurant man aernl, Steve Nelson, was found dead there. Reporter: It's a tragedy all too common in winter months. Fire, going to the false. Report of a carbon monoxide alarm. Reporter: A day later, a similar scare. Seven people showing symptoms of carbon monoxide poisoning were evacuated and sent to the hospital. It's a colorless, odorless poison, but the effects are quickly felt. The treatment for people who suspect or know that they have carbon Mon oxi iide poisoning are to get out of the area. Get clean air. Reporter: Most states, including New York, do not require them in restaurants or malls. Now as mentioned, this legal seafoods was not required to have a monitor. It didn't have one. Is the restaurant's owner says detecters will be placed in all restaurants. It's key to place them low to the ground. If it's placed too high up, it may take too long to provide a vital warning. Good information. Thank you so much.

This transcript has been automatically generated and may not be 100% accurate.

{"id":22647812,"title":"Carbon Monoxide Leak Kills One, Poisons Dozens","duration":"3:00","description":"New information reveals that the New York restaurant did not have a carbon monoxide detector.","url":"/GMA/video/york-legal-seafood-carbon-monoxide-leak-kills-poisons-22647812","section":"GMA","mediaType":"Default"}